Dr. Relling, along with Dr. Strom, will continue to direct the Liver Tissue Core, which provides critical services for a large number of PAAR investigators. The purpose of this Core is to maintain a controlled, shared source of well-characterized liver tissue for research regarding drug-metabolizing enzymes (e.g. CYP3A, UGT1A1, UGT2B7), as well as related regulatory genes (e.g. PXR, CAR) expressed in hepatic tissue. The Liver Tissue Core is physically located in alarmed, monitored -70C freezers at SJ. Availability of this Core has the following advantages: (1) quality control, standardization, and documentation of source, initial organ collection, processing, freezing, and storage; (2) quality control over subcellular fractionation procedures for isolation of microsomes, cytosol, RNA, and DNA; (3) maximal efficiency of use of tissue, e.g. cytosol, microsomes, and genomic DNA for different researchers' projects may all be isolated from the same liver tissue; and (4) centralized and confidential record-keeping for liver characteristics: e.g. drug metabolism phenotype for various cytochrome P450 enzymes, expression of splice variant transcripts, drug intake history histopathologic assessment, and germline genotypes for polymorphisms.